1. Field of the Invention
This invention relates to a magneto-optical recording medium and, more particularly, to a magnetic field modulation type overwritable magneto-optical recording medium. The present invention also relates to a film forming method for forming a diamond-like carbon film on an object, such as the above-mentioned magneto-optical recording medium, by RF plasma CVD.
2. Description of the Related Art
Up to now, a light modulation system or a magnetic field modulation system has been used as a recording system for the magneto-optical recording medium. With the magnetic field modulation system, an objective lens 49 for laser light radiation and a magnetic head modulation head 48 are arranged floating over a magneto-optical disc 50, as shown in FIG. 1.
With the magnetic field modulation system, the current allowed to flow through the magnetic head modulation head 48 is varied, at the same time as the laser light beam is continuously illuminated on the disc, for varying the magnetic field for overwriting new signals irrespective of the direction of magnetization of the recorded signals.
Referring to FIG. 2, the magneto-optical disc 50 has, as a recording layer 56, a dielectric film 52, a magnetic film 53, a dielectric film 54 and a reflective film 55, layered in this order on a polycarbonate substrate 51. On the reflective layer 55 is further layered a photocurable resin 57, such as UV curable resin, for preventing corrosion of the recording layer 56.
Although the magnetic field modulation head 48 and the magneto-optical disc 50 are out of contact with each other, they are proximate to each other, so that some external force occasionally gives rise to physical contact between the magnetic field modulation head 48 and the magneto-optical disc 50. There are also occasions wherein the foreign matter is intruded into a space between the magnetic field modulation head 48 and the magneto-optical disc 50. In such case, the photocurable resin 57 directly transmits the impact caused by contact of the disc with the magnetic field modulation head 48 or by intrusion of foreign matter to the recording surface 56.